A gear transmission is known that has an internal gear and an external gear, one of the gears eccentrically rotating while meshing with the other of the gears. An example of this type of gear transmission is disclosed in, e.g., International Publication No. WO2007/125835. In the description below, International Publication No. WO2007/125835 will be called Patent Document 1. The gear transmission of Patent Document 1 comprises an internal gear, an external gear, a crankshaft and a two-stage gear. The crankshaft extends alongside the axis of the gear transmission. The crankshaft has an eccentric body. The eccentric body engages with the external gear. When the crankshaft rotates, the external gear eccentrically rotates while meshing with the internal gear. The external gear rotates relative to the internal gear in accordance with the difference in the number of teeth of the external gear and the number of teeth of the internal gear. A first gear is affixed to an end of the crankshaft. The first gear meshes with one gear of the two-stage gear. A second gear meshes with the other gear of the two-stage gear. The second gear transmits torque from the motor to the two-stage gear.